The present invention relates generally to agricultural machinery and, more particularly, to an apparatus and method for adjusting the sieve opening in the cleaning mechanism of a combine harvester.
Cleaning mechanisms are employed in agricultural harvesting machines to remove chaff from harvested and threshed crops. Often, several sieves will be used in combination in the cleaning mechanism. Each sieve is provided with a plurality of adjustable surfaces, or louvers, with opening widths between the louvers. In operation, these opening widths must be matched to the quantity of crop being cleaned and to the type of grain being harvested in order to achieve an optimum degree of cleansing. It is known to set the opening width of sieve louvers by hand by means of an adjusting lever while the cleaning mechanism is inoperative.
Furthermore, from utility model DE-GM 7145564, it is known to install an electric-motor-driven, sieve-opening adjustment device in a sieve or in a sieve frame. The adjusting device is formed by an electric motor and a spindle regulator which is connected thereto. The electric motor is located on the crop inlet side of the cleaning mechanism and its shaft is aligned in the direction of motion of the sieve. An adjusting bar is placed below the saddle portion of a sieve such as to be protected from the crop flow, one end of said bar being in engagement with an adjustment rail through the intermediary of an adjusting lever and its other end being provided with a threaded portion. An axially fixed spur gear driven by an electric motor engages the thread so as to allow any desired adjustment to be made. The adjusting bar moves in the same direction as the sieve, or in the opposite direction thereto, in dependence on the direction of rotation of the motor. Furthermore, a measuring device is installed on the adjusting bar for determining the opening width of the sieve, this width then being indicated on a display device in the driver""s cab. The operator of the machine adjusts the opening width by hand or by means of a switch in the driver""s cab until the desired sieve opening is indicated on the display device.
All of the rotating parts in the adjusting device such as the motor shaft, the spur gear, the screw-thread, the adjusting bar and the measuring device are aligned along the axis of movement of the sieve insofar as their actuating directions or rotational axes are concerned. This arrangement is disadvantageous as regards the stability of the adjustments made to the sieve and the consistency of the readings made by the measuring device. The inertial forces occurring in the individual components as a result of the vibratory motion lead to axial movements of the individual components and cause unnecessary wear in the bearings and guides. This in turn, leads to premature failure of the adjusting or measuring device. Another disadvantage of this arrangement arises from the position in which the adjusting motor and its step-down gearing are installed. These are located above the fan on the crop inlet side of the sieve and are difficult to access once they have been installed. The adjusting mechanism, the electrical connections to the motor and the measuring device can only be reached with great difficulty when maintenance work or dismantling of the sieve is required.
Another automatic adjusting device for sieves is known from DE-GM 9112209. A linear drive is mounted on the wall housing of the cleaning mechanism. The adjusting movement is transmitted, by means of Bowden cables, through the side wall of the cleaning mechanism to the adjusting lever of the currently operable, moveable sieve. The vibratory motion of the electric-motor-driven adjusting device is decoupled by the Bowden cable. The length of the path traversed by the linear drive during the course of the adjustment is measured with the aid of the actuating member therefor and serves to determine the opening width.
This adjusting device has the disadvantage that the length of the adjustment path from the adjusting mechanism to the louvers of the sieve is very long and includes many coupling points. A considerable amount of unavoidable play thereby arises throughout the whole of this adjustment path. The determination of the opening width of the sieve can then only be sufficiently precise, for as long as the play in the mechanical parts of the adjusting device remains unaltered. This play increases in step with the overall running time of the adjusting device so that the retention of a reproducible setting for the sieve inevitably worsens. A further disadvantage arises from the actual construction of the adjusting device. It is frequently the case, that the sieves will be removed from the cleaning mechanism at least once a year for inspection and cleaning purposes. To this end, the connections between the linear drive and the sieves have to be interrupted. The Bowden cables have to be detached from the adjusting levers for the sieves, this thereby signifying increased dismantling costs and, in addition, having a non-recoverable effect upon the play in the adjusting device due to the disruption of at least one coupling point.
It is known from the prior art to set the opening width of the sieve by following a certain procedure. A new opening width for the sieve is defined by the machine operator from the driver""s cab of the combine harvester. Before the newly desired opening width is set, the automatic, electric-motor-driven adjusting device sets the sieve opening into one of its end positions (i.e. the maximum or minimum opening width, which is determined with the aid of the measured position of the actuating element in the adjusting mechanism). Thereafter, the new opening width is set up automatically from the adopted zero position. In determining the required length of the adjustment path, a certain, one-off determination of the play in the adjusting device is taken into account by additionally adding-on that length of adjustment path which is required to balance out the play, to the length of adjustment path which it is known is required for the desired opening width so as to thereby obtain the true adjustment path length for the adjusting mechanism. In the known devices, the amount of play relative to the required length of adjustment path is comparatively large and, moreover, increases with an increasing number of adjustments. For subsequent adjustments, the play needs to be determined afresh and this must then be taken into account in an appropriate manner on each occasion. If an adjustment to the sieve opening occurs while the cleaning mechanism is in operation, this adjustment process will lead to a temporary, completely false setting for the opening width. An unnecessary crop loss will thereby ensue.
The adjusting devices for the sieves in combine harvesters known from the state of the art do not fulfil the requirements of an automated process for adjusting the opening width of the sieves in regard to the durability or the functional reliability thereof nor as regards the reproducibility of an opening width.
It is an object of the present invention to provide an adjusting device sieves which overcomes one or more of the deficiencies discussed above.
An object of the present invention is to provide an improved means for adjusting sieve openings in cleaning mechanisms of combine harvesters.
Another object is to provide a sieve opening adjusting device with greater functional reliability.
Yet another is provide an adjusting device that produces more consistently reproducible adjustments of the sieve opening width.
Another object of the present invention is to provide a more reliable method for determining the position of the sieve opening adjusting means relative to a particular opening width so that further adjustments of the sieve opening may be calibrated.
In accordance with the invention there is provided an adjusting mechanism connected with a vibrating sieve having louvers and opening widths between the louvers in a cleaning mechanism of a harvesting machine. The sieve vibrates in a particular direction. In one embodiment, the adjusting mechanism is in the form of a linear drive powered by a brushless electric motor wherein the force of the electric motor is transferred to the linkage by rotating components. The linear drive actuates in a direction along an axis which differs from the vibratory direction of the sieve. The rotating components of the adjusting mechanism are also disposed along an axis which differs from the vibratory direction of the sieve. In another embodiment, the actuation of the linear drive and the rotating components are disposed perpendicularly to the vibratory direction of the sieve.
A method of adjusting the device embodying the present invention includes a detecting means which is activated when a particular opening width is reached and a position sensor which constantly measures the position of the adjusting mechanism. The sieve opening is adjusted in one direction until the particular opening width is reached and the detecting means is activated. The particular opening width is then associated with the position of the adjusting device as measured by the position sensor at the time the detecting means is activated. This association allows calibration of further adjustments to the sieve opening.
The above and other objects, aspects, features and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings.